Toolbox Talks

Pressure Reducing Valves

Short safety talk on the prevention of hoses exploding while transferring nitrogen.

Author: Star Refrigeration

Pressure Reducing Valves

An engineer was injured recently when a coiled hose he had connected to a Nitrogen cylinder exploded.

A combination of circumstances led to the accident, the main ones being:

1. The previous user of the regulating valve had left the adjusting screw wound right in. In this position the regulator would deliver maximum pressure and flow at the outlet.

2. The engineer, after connecting the regulator to the Nitrogen cylinder and the pressure system, did not check that the adjusting screw of the regulator was wound all the way out before opening the nitrogen cylinder valve. In this position the regulator would prevent any pressure or flow at the outlet.

As a result, when the cylinder valve was opened, full flow and outlet pressure of 40 Bar from the M 600 Nitrogen regulator passed into the hose, as a result of which it exploded almost instantaneously. It was fortunate that no serious injury was sustained.

The engineer had sore ears (noise and pressure release) and a sore face (flying debris).

Clearly the consequences could have been much worse.

Remember:

For your own safety when using pressure-reducing valves of any type e.g. oxygen, acetylene, nitrogen, etc.

A. Ensure that when you finish using a pressure-reducing valve, always unscrew the adjuster or remove it entirely.

B. Before fitting a pressure-reducing valve you must ensure that you unscrew the adjuster or remove it entirely.

C. Check the allowable pressure of the equipment being connected. Where appropriate ensure a relief valve is fitted.